| Hardware and OS | Realme Narzo 21A | |
| Operating system | Android v10 (Q) | |
| Processor | Octa-core (4x2.0 GHz Kryo 260 Gold & 4x1.8 GHz Kryo 260 Silver) | |
| Chipset | Qualcomm SDM665 Snapdragon 665 (11 nm) | |
| Internal Storage | 64 GB | |
| GPU | Adreno 610 | |
| RAM | 4 GB | |
| Camera | Realme Narzo 21A | other phones |
| Main camera | 12 MP 2 MP 2 MP | |
| Autofocus | Yes | |
| Camera features | Digital Zoom, Auto Flash, Face detection, Touch to focus | |
| Flash | Yes, LED Flash | |
| Front camera | 8 MP | |
| Front camera resolution | 8 MP Primary Camera | |
| Video recording | Yes | |
| Connectivity | Realme Narzo 21A | other phones |
| Bluetooth | Yes, v5.0 | |
| SIM size | SIM1: Nano, SIM2: Nano | |
| Dual SIM | Dual SIM, GSM GSM | |
| GPS | with A-GPS | |
| Network support | 4G , 3G, 2G | |
| USB connectivity | Mass storage device, USB charging | |
| WI-FI | Yes, Wi-Fi 802.11, b/g/n | |
| Multimedia | Realme Narzo 21A | other phones |
| Audio jack | 3.5 MM | |
| Loudspeaker | Yes | |
| Battery | Realme Narzo 21A | other phones |
| Capacity | 5000 mAh | |
| Type | Lithium-ion Polymer | |
| User replaceable | No | |
| Design | Realme Narzo 21A | other phones |
| Colors | Glory Silver, Victory Blue | |
| Height | 164.4 mm | |
| Width | 75.4 mm | |
| Thickness | 8.9 mm | |
| Weight | 195 grams | |
| Features | Realme Narzo 21A | other phones |
| Fingerprint sensor position | Rear | |
| Fingerprint sensor | Yes | |
| Other sensors | Accelerometer, Proximity, Compass | |
